The coolant pump V50 is electrically powered and is operated when the ignition is switched on, its function is to continue circulating water around the engine/heater matrix when the engine is switched off, so that the heater output does not drop-off. Not only this, it ensures that there is no localized overheating in the engine block (or elsewhere) or large temperature deviations in the coolant system when the engine switches off in Ecomatic operation by ensuring the coolant is still circulated around, therefore, it is sensible to fix this if yours is non-operational not only for comfort but for long-term engine and cooling system reliability.

The 2-pin connector as well as connection pins are notorious for corrosion on this water pump, disconnect the connector and spray with electrical contact cleaner.

This pump can be replaced without having to remove anything other than the pump itself, the rubber mountings can also be installed correctly into the clutch positioner console bracket from underneath the car using angled and straight pin-nose pliers if they have popped out, it is not necessary to remove the clutch positioner console bracket to re-install them correctly.

This replacement pump is slightly smaller than the original pump originally fitted to the vehicle, however, it still fits inside rubber mountings appropriately and does not pose a fitting problem.

VW part number: 251 965 561 B / 251965561B
Bosch part number: 0 392 020 024 / 0392020024
Additional information: http://www.boschmotorsandcontrols.co.uk ... /index.htm (as can be seen from the link, more powerful versions exist, however, this is the correct replacement specified by Volkswagen, in addition, there is hardly any reduction in heat output to the interior when the engine-driven pump is switched off, even on fan speed 4, suggesting that the circulation speed of the pump is more than sufficient to carry heat away from the engine).
Dealer price: £110-120
Motor factors RRP: £80-90

This is also the same part number as the water pump that is used on the VR6.

After making many phone calls, the cheapest price (by a fairly considerable amount) was from http://www.vwspares.co.uk - Thanks to them once again for the good price and service.

This pump actully started out in the VW parts bin for the T3 Transporter turbo diesel (JX engine), hence the 251 part number. On those it helped shovel coolent about when coolent temprature got over 105°C, sounds alot but its most likely to happen just after shutting down a hot engine so helps shift excess heat from the head. I do howerver think the temprature sensor is a bit high. I think the VR6 setup used a much lower switch, as probubly do the later TDI engines with this setup. My T3 doesn't get hot enough to triger it (I can tell as 4WD models also have a turbo cooler fan on the same electric circuit which you can hear running). VW obveously thought it might go unused for some time so installed another relay to fire it up when the starter motor is running to stop it seazing, 19 years later mines still running so it was probubly worth the effort.

The pump on the golf is nackered though, guess the constant running shortens the life somewhat. I know Brickwerks sell a meyle branded version for £85, and they're stock is usally good quality (in my experience, specalist garages that sell parts are much better than motorfactors as they soon get a feal for what rubish and don't want to redo work on warantee.

They do also sell a Meyle version for even cheaper than the Bosch, when I spoke to them, but I asked them to get a Bosch for me, and was suprised at even that price. If you phone them up I'm sure they'll be able to give you a price.